The purpose of the proposed SBIR project is for C-Motion to enhance and commercialize a powerful mathematical muscle model (developed in the laboratory of Dr. Jerry Loeb) within an interactive program (Virtual Muscle) for experimenting with dynamic simulations of neuromuscular control. It will allow investigators to explore empirically the behavior of customizable muscle models in forward dynamic simulations, using a graphical user interface and automated testing protocols. In Phase I, we will: determine model parameters for human muscles; implement the model in Visual C++, optimizing for speed of the calculations and allowing implementation as an actuator in commercial modeling programs; develop a testing program for simulation of the contraction of a single muscle, and test the output sensitivity to perturbations in model parameters: develop a custom simulation of two- dimensional human and monkey arm movements now being studied by Dr. Loeb and colleagues; design a command script scheme for automated testing; and define the specifications for post-processing and compilation of test data into a formatted report. In Phase II we will develop a program for exploring approaches to calculating individual muscle forces acting at a joint, leading to clinical and research evaluations of movement disorders. PROPOSED COMMERCIAL APPLICATIONS: A commercial muscle model that is easy to use, and captures accurately the complex mechanical properties of real muscles and tendons, will be useful to researchers who must understand neuromuscular control in order to address clinical rehabilitation issues. Virtual Muscle will be a key element of the next generation of clinical movement analysis software providing an environment for research in neuromuscular control in the development of new strategies for solving the general distribution problem and estimating individual muscle forces.